Video codecs specifications such as the HEVC base specification [1] and its extensions such as the multi-view extension [2] [3] usually inherit mechanisms to signal the layer to which each coded chunk of video data belongs to in a layered coding scenario. The signaling mechanism needs to be readily available, cp. the layer identifier in den NAL unit header (nuh_layer_id) in HEVC as given in the table in FIG. 1.
With its finite size in terms of bits, the respective HEVC syntax element allows for 64 values to be used to identify scalable layers, views and/or depth. For multi-view video using the current HEVC NAL unit header syntax, this for example implies a constraint of 64 views or 32 view plus depth combinations as maximum. While this is sufficient for many common stereo view scenarios and other applications, huge camera arrays with more than 100 views for applications like light field imaging [4], [5] or holographic displays [6] may use an extendable mechanism for signaling a larger space of layer identifiers.
Furthermore, structuring the space of layer identifiers by grouping certain layers or views with respect to their coding dependencies or spatial relation to each other may be of benefit. Further, providing a compact representation of the coding dependencies in the structured layer identifier space is also of benefit as deriving such information from already available information within the coded video bitstream may involve intolerable computational resources.